Field of the Invention
The present invention relates to substrate supports such as susceptors and substrate holders for use in chemical vapor deposition apparatuses for forming a film on the surface of a substrate (e.g., by subjecting reactive gas to reaction). The invention also relates to a semiconductor manufacturing apparatus provided with such a substrate support.
Background Art
Japanese Laid-Open Patent Publication No. 2006-60195 discloses a substrate support for supporting a substrate during chemical vapor deposition. The portion of this substrate support on which the substrate (or wafer) is mounted is formed at least partially of a graphite material covered with a tantalum carbide (TaC) film, and the portion of the substrate support surrounding that portion is formed of a graphite material covered with a silicon carbide (SiC) film.
It is common that the graphite material of a substrate support is covered with an SiC film, since if the graphite material is exposed, it degasses, releasing boron, etc., which alters the ambient gas atmosphere around the substrate. However, it has been found in some cases that the portion of SiC film that has been brought into contact with the substrate particularly heats up to a high temperature and undergoes close-space sublimation. This close-space sublimation problem can be avoided by covering the graphite material with a TaC film, which has a higher melting point than an SiC film and has excellent heat tolerance and chemical stability, so that the substrate comes into contact with the TaC film.
It has been found, however, that TaC films are liable to crack and peel off, exposing the underlying graphite material. Further, both SiC and TaC films do not adequately adhere to graphite material and hence are likely to peel away from the graphite material. Therefore, prior art substrate supports covered with these films have the problem of low durability.